1. Field of the Invention
The field of the invention is data processing, or, more specifically, methods, apparatus, and products for failover in a data center that includes a multi-density server.
2. Description of Related Art
In data centers today, a server having a single rack space form factor may, in fact, house many independent servers. Such a server is referred to as a multi-density server. While independent servers may share some resources of the multi-density server, independent servers within the same multi-density server may each include separate central processing units (CPUs), separate primary memories, separate communications adapters, separate local power supplies, and so on. Each independent server may execute a separate and independent operation system and different workloads. Other servers in the data center may interact with each independent server as if the independent server was a server in a single rack space form factor. That is, the physical housing of the independent server does not factor into another servers interaction with the independent server.
Problems occur, however, in migration for purposes of high availability and failover. Migration due to failover is often carried out with respect to physical affinity. A workload executing on a first server is often migrated, during failover, to the physically closest available server. In multi-density servers, however, a failure of one independent server often leads, due to the affinity algorithms, to migrating the failing independent server's workload to another independent server of the same multi-density server. Failures, however, in an independent server often require the entire multi-density server (including all independent servers) to be taken off-line for repair. Also, a single failure detected in one independent server may find be caused by resource failure of the multi-density server that are shared amongst all independent server. As such, a failure of one independent server represents higher probability of failure in another independent server in the same multi-density server than a failure in another server housing altogether. In each of these examples, migration of workload from one independent server to another within the same multi-density server is inefficient and may possibly result in failure to provide high availability.